Some people like cutting their lawn. Others, not so much. There are two options for those in the latter camp: a lawn service or a robotic mower, otherwise known as a lawn bot or mower bot. Homeowners are turning to these small machines to help them regain some enjoyment during their summers. The bot stays busy cutting the lawn while you relax in the pool or go away on vacation. If that sounds like your kind of arrangement, read on for our reviews of the most promising models.
Take a look at quick info of the five best robot lawn mowers, then scroll down for buying advice and in-depth reviews of these and others.
A lawn bot consists of a plastic chassis on which are mounted mower heads, a battery, drive motors, and one or more circuit boards to assess ground speed, direction, tilt, and obstacles. After you buy one, you (or the dealer) bury a perimeter wire in the lawn. That wire leads back to the charging station, which is plugged into a 120-volt exterior outlet. The charging station contains a generator that sends a low-power signal out on the wire. As the mower approaches the wire, it picks up the signal, stops, turns around, and heads off in a random direction.
When its battery is nearly depleted, the mower heads back to the station for recharging, which can take anywhere from one three hours. Some mowers have removable batteries. You can let the mower recharge or plug in new batteries and send the mower back out on its mission while the batteries recharge elsewhere.
Unlike a walk mower that spins a single, large steel blade, a robotic mower spins smaller cutting heads with fold-away steel blades. If the blade strikes a fixed object left in the grass, the impact causes the blade to fold back into the head.
Robot mowers are best suited to small, simple yards that are relatively smooth and flat. Yards with more complex geometry require you to lay more ground wire, and the more wire you lay, the more you increase the likelihood of a break from somebody digging in the yard or a tunneling rodent chomping through the wire. Although Husqvarna makes an all-wheel-drive mower (the 435 X) capable of climbing steep slopes and handling rugged conditions, it doesn’t take much to stop a robot. A low spot, a mushy zone, pine cones, fruit and nuts, and fallen branches can all stop or impair a bot’s progress by dragging underneath it until they stop the mower dead.
Also, don’t get lulled into a sense of complacency with one of these machines and forget that its undercarriage needs to be cleaned and its lightweight steel blades sharpened or replaced. None of this is any more than the attention that a gas-engine or battery mower requires.
How We Selected These Mowers
The mowers below are a cross-section, representing the most promising on the market in a range of prices and capabilities, with nearly every manufacturer represented. We picked a range: tiny mowers suited for the smallest possible yard to commercial tanks big enough to trim the sweeping lawns around a college campus. We haven’t tested these in person yet , so we relied on our own experience mowing lawns and took into account specs like the mowing area, battery life, and height settings.
Claimed mowing area: 0.4 acre | Run time: 1 h, 10 min | Mow height: 0.8 to 2.4 in.
As a pioneer in robotic mowing, Husqvarna has more experience in the category than anybody else, and that’s evident with this product. The 22-pound, three-cutter-head mower can climb a 22-degree slope and is rated for 70 minutes of straight mowing, ranging over a 0.4-acre area. That’s 17,424 square feet of grass, a reasonably good-size lawn by any standard. A shrill alarm sounds if a would-be bot robber tries to make off with it, and even if he or she does, its built-in GPS will help you locate it.
Claimed mowing area: 5 acres | Run time: 1 h, 50 min | Mow height: 0.8 to 3.9 in.
A less expensive alternative to the 315X above is the 115H. It’s rated for the same surface area (0.4 acre) but a shallower 17-degree slope. Otherwise, it has many of the same features (anti-theft, three-cutter head configuration, and a cut width of 8.6 inches). But its run time is 60 minutes, not 70, so it will make more trips to the charger. Ergo it will take slightly longer overall; the mower would be more visible and will be out on the lawn more to make up the difference, given a random cut pattern. Its 60-minute charge cycle is the same, however, as the 315X.
―EASY TO STORE―
Gardena 4069 R80Li
Claimed mowing area: 0.2 acre | Run time: 1 h, 5 min | Mow height: 0.8 to 1.8 in.
This is one of the lightest robotic mowers we know of. It weighs just 13.4 pounds, which makes it easy to store on a shelf during the off season. The petite bot cuts a 6.3-inch swath per pass, making it a good fit for small yards or those with intricate landscape details where a larger mower won’t fit. If that sounds like your lawn, it might be a good fit for you. But just because it’s small doesn’t mean it’s an anemic cutter. Gardena rates it for a 14-degree slope and 60 minutes before it needs a charge. It’s also the only mower we know of that’s equipped with a frost sensor. When it detects some, it stops mowing and heads back to the charger.
Honda Miimo HRM 310
Claimed mowing area: 0.4 acre | Run time: 3 h, 45 min | Mow height: 0.8 to 2.4 in.
A particularly intriguing feature of this Honda is that you can pre-adjust its settings based on the seasons. Like in the high-growth conditions of spring, it can cut more frequently and for longer sessions. And in late summer, when grass grows more slowly or even goes dormant, it can mow less often. This saves wear and tear on both the lawn and the mower. Still, the petite Miimo is rated for a bit more than a third of an acre of grass. That may not sound like much, until you realize it’s about 15,000 square feet, more than enough capacity for small quarter-acre lots. Another feature that distinguishes it from the rest of the pack is that it can mow a repeating long and narrow V-shaped pattern. That helps it cope with long, narrow rectangular pieces of lawn and is far more efficient than the mower constantly traversing back and forth across the rectangle.
―RECHARGE TWO WAYS―
Claimed mowing area: 0.13 acre | Run time: Unlisted | Mow height: 1.5 to 3 in.
The WR165 is unique in that it takes the same 20-volt battery as used in other Worx (20-, 40-, and 80-volt) power tools. You can put in a freshly charged battery to power it and increase its cutting time, or you can allow the mower to charge conventionally, by making its way back to the charging station. Worx provides no estimated run time for the bot but rates it to cut capacity as 1/8 of an acre or 5,445 square feet of grass (picture a rectangle 20 feet wide by 272.3 feet long, and you get the idea). Like larger robotic mowers, it’s equipped with anti-theft tracking, a 20-degree slope rating, and the ability to handle up to a three-inch cutting height.
―FOR TINY-YARD MOWING ―
Claimed mowing area: 0.2 acre | Run time: 3 h | Mow height: 0.5 to 1.75 in.
For a tiny yard, consider the RX20. It’s rated for a truly small space (0.2 acre or 2,178 square feet) and a very shallow maximum slope of 8.5 degrees. But its petite cutting capability doesn’t reflect its full ability, which is quite high tech. You can integrate it into the Amazon Alexa Smart Home system for voice control, for example. And you don’t need to bury its boundary wire; Robomow says pegging it to the lawn surface is sufficient. The company estimates typical setup for a small yard takes about an hour.
―GOOD AT BORDERS―
Claimed mowing area: 0.5 acre | Run time: 80-100 min | Mow height: 0.8 to 3.5 in.
The RS630 is the RX20’s big brother–a lot bigger. It weighs 47 pounds and is rated for an 80- to 100-minute mowing cycle to cut approximately half an acre (21,780 square feet), even including a 20-degree slope. Its cutting width is 22 inches and that includes cut-to-the-deck-edge capability, which means the mower trims right to the grass edge above the perimeter wire. And that translates to less trimming. On a half-acre lawn, that’s no small matter. As you might imagine, it takes longer to charge its hefty battery pack (90 to 110 minutes).